In several communications systems the data to be transmitted is compressed so that the available bandwidth is used more efficiently. For example, the Moving Pictures Experts Group (MPEG) has promulgated several standards relating to digital data delivery systems. The first, known as MPEG-1 refers to ISO/IEC standards 11172 and is incorporated herein by reference. The second, known as MPEG-2, refers to ISO/IEC standards 13818 and is incorporated herein by reference. A compressed digital video system is described in the Advanced Television Systems Committee (ATSC) digital television standard document A/53, and is incorporated herein by reference.
The above-referenced standards describe data processing and manipulation techniques that are well suited to the compression and delivery of video, audio and other information using fixed or variable length digital communications systems. In particular, the above-referenced standards, and other “MPEG-like” standards and techniques, compress, illustratively, video information using intra-frame coding techniques (such as run-length coding, Huffman coding and the like) and inter-frame coding techniques (such as forward and backward predictive coding, motion compensation and the like). Specifically, in the case of video processing systems, MPEG and MPEG-like video processing systems are characterized by prediction-based compression encoding of video frames with or without intra- and/or inter-frame motion compensation encoding.
Present electronic distribution systems typically do not strike an appropriate balance between flexibility and security for the purposes of some information distribution applications. For example, to enable the electronic distribution of motion pictures (i.e., film) and other entertainment video applications, it is necessary to dynamically process “trailers” (i.e., short previews of coming attractions”) on a location by location basis, in addition to full length motion pictures. With respect to security, it is obviously necessary to incorporate a high level of security, ideally using a multi-layer security approach, such that the valuable intellectual property transmitted within the system is not compromised.
Therefore, a need exists in the art for a secure and flexible method and apparatus for distributing information such as high-value motion pictures and other audio-video information, as well as other forms of data. Additionally, it is seen to be desirable to provide enhanced security for various media, such as digital versatile disk (DVD) and other media.